One of Australia's biggest political donors, who rubbed shoulders with serving and former prime ministers, has been accused of engaging in clandestine activities to "advance the interests of the People's Republic of China".

The allegations involving Chau Chak Wing, an Australian citizen who has also donated $45 million to Australian universities, are detailed in a defamation case in the Federal Court.

Mr Chau launched the defamation action against Fairfax Media and ABC's Four Corners after a series of stories that showed the Chinese-born property billionaire was a key member of Chinese propaganda organisations in Australia, and that ASIO had warned political parties about their associations with him.

Now, barristers for investigative reporter Nick McKenzie, Fairfax Media and the ABC have filed documents in the Federal Court alleging they had "reasonable grounds to suspect" that Mr Chau "betrayed his country [Australia], in order to serve the interests of a foreign power, China, and the Chinese Communist Party by engaging in espionage on their behalf".

The documents allege that the Chinese Communist Party uses "agents" to "learn about, influence and subvert" the policies of foreign governments, including Australia's.

"There are reasonable grounds to believe that [Mr Chau] ??? donated enormous sums of money to Australian political parties as bribes intended to influence politicians to advance the interests of the People's Republic of China, the Chinese government and the Chinese Communist Party," say the documents, authored by barrister Matt Collins, QC, and filed on Friday.

The investigative reporting earlier this year revealed that ASIO had concerns about clandestine influence operations in Australia carried out by Communist Party organisations, including the United Front Work Department.

The reporting also revealed that ASIO had warned the major political parties about Mr Chau's political donations and his close connection to the Chinese Communist Party.

The documents also allege that Mr Chau was party to a conspiracy to pay a $200,000 bribe to the president of the United Nations, John Ashe???, and that he engaged lobbyist Sheri Yan, "whom he knew to be a corrupt espionage agent of the Chinese government" to help advance the Communist Party's interests.

Ms Yan's Canberra residence was raided by ASIO in October 2015 over allegations she engaged in espionage. She was sentenced to 20 months' jail in the US for bribing Mr Ashe to attend a conference hosted by Mr Chau. A $200,000 payment that Ms Yan admitted in court was used to bribe Mr Ashe was allegedly provided by a company owned by Mr Chau.

Ms Yan's husband is a former senior Australian intelligence analyst, Roger Uren???.

Mr Chau's defamation case, run by Sydney defamation specialist Mark O'Brien???, will be closely watched in Canberra, Beijing and Washington as it is likely to test allegations not only about Mr Chau's activities but Beijing's agenda and the operations of highly opaque parts of the Communist Party apparatus.

In the wake of the Fairfax Media stories, Attorney-General George Brandis announced Australia would reform its anti-foreign interference laws, while Labor leader Bill Shorten banned his party from taking donations from Mr Chau and a second donor with close CCP ties.

The defence filed by Mr Collins, QC, also contrasts Mr Chau's public denials in a media interview that he had any knowledge of the CCP's lobbying arm, the United Front Work Department, with photos and other evidence showing Mr Chau meeting with UFWD officials and participating in alleged United Front events and organisations.

Mr Chau's defamation action, in which he denies any impropriety or clandestine allegiance to the CCP, mirrors an earlier, ongoing legal action he has issued against Fairfax Media and John Garnaut???, a former China correspondent.

This case is also looming as a significant legal battle, partly because Mr Garnaut left journalism to become a federal government adviser on China in the office of Prime Minister Malcolm Turnbull and, later, for the Department of Prime Minister and Cabinet.

Mr Chau has donated more than $4 million to the major political parties since 2004, as well as making large donations to universities. In his defamation actions against Mr Garnaut and Mr McKenzie, Mr Chau says the imputation these donations were in any way improper is defamatory and false.

However, the statement of defence says it could be inferred that Mr Chau donated to "put himself in a privileged position that would enable him, among other matters, to learn about the policies of the Australian government and opposition, and to gain privileged access to politicians and businessmen".

"[Mr Chau] intended to use that privileged access to attempt to influence Australian politicians and businessmen so as to advance the interests of the PRC, the government of the PRC and the CCP," the court documents state.

Politicians named in the document as having met with Mr Chau include former prime ministers John Howard, Kevin Rudd, Tony Abbott and Julia Gillard, as well as Foreign Affairs Minister Julie Bishop and former foreign affairs minister Bob Carr.